Pulp board



Patented m 31,1932

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msnx, A. oonromrron or new msnx rum noann Ho Drawing.

Our invention relates to pulp board and comprises, broadly speakipf, pulp board provided with a binder of ontan wax. A

board embodying our invention may be made.

of any of the usual paper pulps, either rag or wood fibre, or may be made of straw, bagasse or other suitable material and may be produced in laminated or homogeneous form. We have obtained our best results with molded pul board which is made by running paper. pup, wood pulp, or the like into a mold and, by means 0 pressure, removing the majority of the water .(see for instance United States Letters Patent No. 971,936 dated October 4,1910, and No. 1,272,566 dated July 16, 1918) and subsequently drying out the remainder of the water by the application of heat. The wax may be added to the fibre either before or after the latter has been shaped into a board. For instance the board' may be dipped into the melted Montan wax for a sufiicient length of time to enable it to absorb a suitable proportion of such wax; or the fibre and the wax, the latter in the form of an emulsion, may be mixed in the beater before molding or laying up the board, although a board made in this manner may not possess as high a degree of tensile or transverse strength as does a board made by the di pin process. We may also 'di the dried can? into a solution of the wax, t ereafter driving out the solvent by heat or otherwise. We have, however, found that by far the best results are obtained. by adding the Montan wax in comminuted form to the beater while the pulp is bein beaten therein. For this purpose it 1s advisa le to grind the Montan wax dry in a ball mill, as fine as possible and then to moistenit with-water and thereafter to complete the grinding in the same will more readily mix with pulp in the'beator as it does not tend to riseto, and float upon, the surface of the water asit would do if added in the form of a dry owder. By adding the Montan wax to the bre in comminuted form we obtain a more equal distribution thereofthroughout the entire "sheet and are enabled to fillup all the spaces between" the l fibres, thus obtaining a more compact and The wet ground Montan wax Application am August is, 1924,. Serial ms. 731,871.

water roof board, having a better surface, and a sorbing less paint when the surface is painted. We can moreover, by this specific method, mix more Mont'an wax with the fibre without having the same squeezed out during the compressing process and thus obtain a board of greater tensile strength. The com minuted Montan wax seems to give results far superior to those obtained by the use of the emulsifiedwax, probably because the former is unchanged (unemulsified).

I The proportion of Montan wax, by weight, to theweight of fibre in-the' final product is preferably from 30% to the exact percentage depending upon the use to which the board is to be put; the greater "the propor-' tion of Montan wax within these limits, the more waterproof will be the finish board and the higher its tensile strength, other things I being equal; on the other hand, the higher the compression to which the saturated board is to be subjected, the smaller would have to be the percentage of Montan wax used. Of

course, no such high percentage of Montan rendered plastic by heating it slightly above the fusion point of the wax. On the other hand, it will not be injured by exposure to the sun when used as roofing or siding for buildings.

.In spite of its hi h tensile and transverse strength, the material may be easily tooled and does not dull tools to thesame extent as will such materials, of equal hardness, which are known to us and which are made of pul treated with other binders. The materia has very ood wearing qualities and can, therefore, eused for various purposes -m which such qualities are important, for mstance, as tread material for protecting steps.

c We do not claim the use of so small, or so large, a proportion of Montan wax to fibre that the advanta hereinabove set forth are not obtained. vz realize, however, that the use of somewhat less and somewhat more than the optimum proportions of 30 to 50 arts by weight of Montan wax to 100 parts y weight of fibre may result in obtaining the advanta es hereinabove stated to a lesser de-' gree an to that extent the use of such proortions would be within the spirit of our invention and the equivalent of the proportions specified in our claims.

A board made as hereinabove described, to which other ingredients have been added without changing its essential characteristics, would fall within the scope of our invention.

We claim:

- 1. Molded pulp board comprising a comressed mixture of from 30 to 50 parts of ontan wax, by weight, to 100 parts of fibre. 2. An article of the character described consisting of fiber board impregnated for a comes suflicien substantial depth with a waxy material which is hard and brittle at high atmospheric temperatures but is suflicientlyfluid at 275. F. to be forced into said fiber board.

3. An article of the character described consisting of fiber board rendered substantially impervious to moisture by having the ores and cells thereof for a substantial depth ed with a hard waterproof waxy material not soften at temperatures below 4. An article of the character described consisting of fiber board impregnated for a substantial depth with a composition in which Montan wax predominates.

5. An article of the character described consisting of fiber board impregnated for a substantial de th with Montan wax.

6. artic e of. the character described consisting of fiber board carrying in "the microscopic pores and cells thereof a waterproof waxy material which remains hard at temperatures below 140 F. but becomes sufliciently fluid at 27 5 F. to be forced into said .pores and cells.

The roeess of improving the characteristics of fi r board which consists in impregnatmg t for a substantial depth with a melted waxy material which is hard and brittle at high atmostpheric temperatures but be y fluid at 275 F. to netrate mto the microscopic pores and ce s of fiber board, and subsequentl allowin the fiber board so treated to coo suflicient y to cause said material to harden therein. Y

GUSTAVE LANDT. HUBEBT LEOPOLD BECHER. 

